Parameter Specification / Typical Value Device Type Protective / Measuring Current Transformer (CT) Primary Rated Current (Ipr) Variable. This is a core parameter determined by the application (e.g., 100A, 200A, 400A, 800A, etc.). The model "MT-105B" defines the mechanical and electrical design, while the primary current is specified upon ordering. Secondary Rated Current (Isr) Standardized: Typically 1 A or 5 A (This is another key ordering specification). Rated Burden 5 kΩ (at the specified secondary current and frequency). This is the impedance of the secondary circuit (including wires and relay/meter impedance) for which the accuracy class is guaranteed. Accuracy Class Typically 5P or 10P for protection, or 0.5, 0.5S, 1 for measurement. This is a critical ordering parameter. Example: "5P10" where '5' is the composite error in %, 'P' is for protection, and '10' is the accuracy limit factor (ALF). Accuracy Limit Factor (ALF) For protection classes (e.g., 10, 15, 20). Defines the multiple of rated current up to which the CT maintains its specified accuracy during faults. Rated Frequency 50 Hz or 60 Hz (as specified). Rated Insulation Level / Voltage Medium Voltage Level, e.g., 12 kV, 24 kV, or 36 kV. This is a primary safety specification and must match the system voltage. Short-Time Thermal Current (Ith) Specified in kA for a short duration (e.g., 1s or 3s). Indicates thermal withstand capability during a short-circuit. Dynamic Current (Idyn) Specified in kA peak. Indicates the mechanical withstand capability against electromagnetic forces during the first peak of a short-circuit current. Core Type / Quantity Often has multiple independent cores (e.g., 2 cores: one for protection class '5P', one for measurement class '0.5S'). Mounting Typically designed for flange mounting or busbar mounting inside metal-enclosed switchgear. Standards Compliance IEC 61869-1 & -2 (or the older IEC 60044-1), and other relevant national standards.